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Efficient refining method of caprolactam

A technology of caprolactam and refining method, which is applied in the field of caprolactam refining, can solve problems such as poor applicability and complicated process flow, and achieve the effects of shortening the production process, wide application range, and reducing waste water discharge

Active Publication Date: 2018-08-17
河北美邦工程科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The purpose of the present invention is to provide a high-efficiency refining method of caprolactam to solve the problems of complex technical process and poor applicability of the existing technical methods

Method used

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  • Efficient refining method of caprolactam

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The process flow of this embodiment is as figure 1 shown.

[0032] (1) The liquid phase rearrangement reaction product from the ammonium sulfate neutralization crystallizer is flashed under the condition of 10KPa (absolute pressure), and the low boiling point substance water and light phase impurities are removed to obtain the flash concentrated liquid. When the mass concentration of caprolactam in the concentrated liquid is 95%, the flash evaporation ends, ammonium sulfate crystallizes out, and then centrifuges at a temperature of 85°C to obtain ammonium sulfate and crude caprolactam oil. biochemical treatment.

[0033] (2) Evaporate the crude caprolactam oil obtained in step (1). The evaporation operation pressure is 15KPa (absolute pressure) and the temperature is 75°C. When the mass concentration of the caprolactam solution in the kettle liquid obtained at the bottom of the evaporation tank is 99%, After the evaporation process is completed, the low-boiling impuri...

Embodiment 2

[0039] (1) The solvent rearrangement reaction product from the ammonium sulfate neutralization crystallizer is flashed at a pressure of 25KPa (absolute pressure), and the light-phase impurities of low-boiling substances are removed to obtain a flash concentrate. When the flash concentrate When the mass concentration of caprolactam in the medium is 90%, the flash evaporation ends, ammonium sulfate crystallizes out, and then centrifuges at a temperature of 90°C to obtain ammonium sulfate and crude caprolactam oil, and the light phase impurities of low boiling point substances enter biochemical treatment.

[0040] (2) Evaporate the crude caprolactam oil obtained in step (1). The evaporation operation pressure is 20 KPa (absolute pressure) and the temperature is 70°C. When the mass concentration of the caprolactam solution in the bottom of the evaporation tank is 96% , to end the evaporation process, the low-boiling point impurities obtained at the top of the evaporation tank enter...

Embodiment 3

[0046] (1) The vapor phase rearrangement reaction product from the solvent evaporator is flashed at a pressure of 30KPa (absolute pressure), and part of the light phase impurities of low boiling point substances are removed to obtain a flash concentrated liquid. When the caprolactam in the flash concentrated liquid When the mass concentration is 85%, the flash evaporation ends, ammonium sulfate crystallizes out, and then centrifuges at a temperature of 95°C to obtain ammonium sulfate and crude caprolactam oil, and the light-phase impurities of low-boiling substances enter biochemical treatment.

[0047] (2) Evaporate the crude caprolactam oil obtained in step (1). The evaporation operation pressure is 25 KPa (absolute pressure) and the temperature is 65°C. When the mass concentration of the caprolactam solution in the bottom of the evaporation tank is 98% , to end the evaporation process, the low-boiling-point impurities obtained at the top of the evaporator enter biochemical t...

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Abstract

The invention discloses an efficient refining method of caprolactam. Rearrangement reaction products obtained in the process of producing caprolactam by rearrangement reaction are subjected to simpleoperations such as flash evaporation, centrifugal separation, evaporative distillation, membrane filtration and crystallization, thereby obtaining high-purity caprolactam finished products and nylon slice products meeting industrial requirements. The method disclosed by the invention is suitable for refining of reactants obtained by gas phase, liquid phase and solvent rearrangement processes and has a wide application range. Compared with a traditional caprolactam purification process, the technology disclosed by the invention has the advantages that caprolactam products with higher quality can be prepared, an intermediate product caprolactam crystal can be prepared into the nylon slice products, production processes are shortened to a certain extent, solvent dosage and wastewater discharge are obviously reduced, and investment and production costs are greatly lowered.

Description

technical field [0001] The invention relates to the refining of caprolactam, in particular to a high-efficiency refining method of caprolactam. Background technique [0002] Caprolactam is an important chemical raw material for synthetic fibers and engineering plastics. At present, domestic production of caprolactam generally adopts a liquid-phase rearrangement system. This rearrangement system is to make cyclohexanone oxime undergo a Beckmann rearrangement reaction in the presence of oleum to generate caprolactam, which is then neutralized with ammonia gas or ammonia water. Unreacted sulfuric acid is purified by benzene extraction, water extraction, ion exchange, hydrogenation, three-effect evaporation and rectification to prepare caprolactam. The conversion rate and selectivity of this method are ideal, but the production process requires a large amount of oleum and Ammonia, a by-product of ammonium sulfate with low economic value, has a long purification process and high...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D223/10C07D201/16
CPCC07D201/16C07D223/10
Inventor 金作宏刘东卢远峰南向竹闫利军魏朝帅刘永英李彦新赵途王素霞
Owner 河北美邦工程科技股份有限公司